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Python 中的 numpy .挤压()

原文:https://www.geeksforgeeks.org/numpy-squeeze-in-python/

numpy.squeeze() 功能是在我们想要从数组的形状中移除一维条目时使用的。

语法: numpy .挤压(arr，axis =无)

参数: arr : 【阵 _ 象】输入阵。 轴:【无或 int 或 int 元组，可选】选择形状中一维条目的子集。如果选择的轴的形状条目大于 1，则会出现错误。

返回: 挤压【ndarray】输入数组，但长度为 1 的维度的全部或子集被移除。这永远是一个本身或一个观点。

代码#1 :

# Python program explaining
# numpy.squeeze function

import numpy as geek

in_arr = geek.array([[[2, 2, 2], [2, 2, 2]]])

print ("Input array : ", in_arr) 
print("Shape of input array : ", in_arr.shape)  

out_arr = geek.squeeze(in_arr) 

print ("output squeezed array : ", out_arr)
print("Shape of output array : ", out_arr.shape) 

输出:

Input array :  [[[2 2 2]
  [2 2 2]]]
Shape of input array :  (1, 2, 3)
output squeezed array :  [[2 2 2]
 [2 2 2]]
Shape of output array :  (2, 3)

代码#2 :

# Python program explaining
# numpy.squeeze function
import numpy as geek
in_arr = geek.arange(9).reshape(1, 3, 3) 

print ("Input array : ", in_arr)  
out_arr = geek.squeeze(in_arr, axis = 0) 

print ("output array : ", out_arr)  
print("The shapes of Input and Output array : ") 

print(in_arr.shape, out_arr.shape)

输出:

Input array :  [[[0 1 2]
  [3 4 5]
  [6 7 8]]]
output array :  [[0 1 2]
 [3 4 5]
 [6 7 8]]
The shapes of Input and Output array : 
(1, 3, 3) (3, 3)

注:

ValueError :
If axis is not None, and an axis being squeezed is not of length 1.

代码#3 :

# Python program explaining
# numpy.squeeze function
# when value error occurs
import numpy as geek

in_arr = geek.arange(9).reshape(1, 3, 3) 

print ("Input array : ", in_arr)  
out_arr = geek.squeeze(in_arr, axis = 1) 

print ("output array : ", out_arr)  
print("The shapes of Input and Output array : ")

print(in_arr.shape, out_arr.shape)

输出:

ValueError                                Traceback (most recent call last)
 in ()
      5 
      6 print ("Input array : ", in_arr)
----> 7 out_arr = geek.squeeze(in_arr, axis=1)
      8 print ("output array : ", out_arr)
      9 print("The shapes of Input and Output array : ")

~\Anaconda3\lib\site-packages\numpy\core\fromnumeric.py in squeeze(a, axis)
   1196     try:
   1197         # First try to use the new axis= parameter
-> 1198         return squeeze(axis=axis)
   1199     except TypeError:
   1200         # For backwards compatibility

ValueError: cannot select an axis to squeeze out which has size not equal to one
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